1. Technical Field of the Invention
The present invention relates generally to a method of cutting slots in a hard material, and more particularly to an improved method of machining slots and material feed holes in a die for molding a honeycomb structure, for example.
2. Background of Related Art
U.S. Pat. No. 4,640,454 to Yamamoto et al. teaches an extrusion die for making honeycomb structures of ceramics used as a catalyst carrier of a catalytic converter for automotive vehicles.
Such honeycomb structures have thin honeycomb walls of the order of 100 .mu.m. The extrusion die, thus, needs to have formed therein slots whose width is of the order of 105 to 110 .mu.m and material feed holes communicating with the slots. Usually, the slots are cut using a disc-shaped rotary cutter having a thickness of 100 .mu.m, and the material feed holes are drilled.
The conventional die machining techniques, however, have encountered the drawbacks in that the drilling of the material feed holes causes burrs to occur at portions of the holes communicating with the slots, thereby resulting in defects in the honeycomb structures and in that the cutter is deformed or shifted out of a preselected cutting path during cutting of each slot because of thinness thereof, thereby resulting in the curved slots.